1. Technical Field
The present invention relates to a technology of tracking an object in a moving image.
2. Related Art
Conventionally, there is utilized a technology of tracking motion of a body such as a person or a substance in a moving image. For example, in one of the motion tracking technologies, when the object is once focused on in shooting a moving image with a digital camera, a digital video camera, or a mobile phone, the object is tracked while continuously focused on.
The body tracking includes initialization processing of deciding on the tracked body from the image of a certain frame and searching processing of searching a body (region) similar to the tracked object decided on in the initialization processing from the images of the next frame or later. In the initialization processing, a partial region of the image can be designated as the tracked object by designating a region in the image with a touch panel or using a well-known face detection or person detection. A template indicating a feature of the designated tracked object is produced in the initialization processing. The tracked object in the image of the next frame is searched by using a degree of similarity to the template in the searching processing. The template is updated according to the tracked object in the image of the next frame in the searching processing.
Examples of the template producing method include a method (for example, see U.S. Pat. No. 6,590,999) for obtaining a color distribution or an edge distribution of the tracked object from a region of the tracked object of the image and a method (for example, see H. Grabner, et. al., “Online Boosting and Vision”, IEEE. Conf. on Computer Vision and Pattern Recognition, PP. 260-267, 2006) for obtaining effective information discriminating between the tracked object and the surrounding region from the region of the tracked object of the image and the surrounding region of the tracked object.
In a technology disclosed in U.S. Pat. No. 6,590,999, the color distribution of the tracked object in the past image is stored as the template, and the region similar to the template is searched in the current image by using a gradient method.
In a technology disclosed in H. Grabner, et. al., “Online Boosting and Vision”, IEEE. Conf. on Computer Vision and Pattern Recognition, PP. 260-267, 2006, in order to discriminate between the tracked object and the surrounding region, information (for example, information on a background color) indicating a difference between the tracked object and the surrounding region is obtained from the image to perform learning as a discriminator of the tracked object, and the tracked object is tracked.
However, in the conventional configuration, when the body (analog) similar to the tracked object exists near the tracked object, unfortunately sometimes the analog is mistakenly tracked instead of the tracked object.
In the technology disclosed in U.S. Pat. No. 6,590,999, the template includes the information on the color or edge distribution obtained from the tracked object, and the analog is detected by the degree of similarity to the template. Therefore, when the analog exists near the tracked object, sometimes the analog is mistakenly tracked.
In the technology disclosed in H. Grabner, et. al., “Online Boosting and Vision”, IEEE. Conf. on Computer Vision and Pattern Recognition, PP. 260-267, 2006, when the analog that is extremely similar to the tracked object exists near the tracked object, because the effective information for discriminating between the tracked object and the surrounding region (including the analog) cannot be extracted, the tracked object cannot be tracked.